MOFs functionalization of 3D printed mullite complex architectures for CO2 capture

• Complex porous mullite structures were successfully printed by Digital Light Processing. • Pure HKUST-1 crystals were synthetized by solvothermal synthesis on mullite supports. • Preliminary CO 2 adsorption tests performed under 1% CO 2 evidenced encouraging results. • Compared to HKUST-1 powder bed, functionalized 3D printed monoliths led to a CO 2 uptake increase up to 51.3%. • Three consecutive cycles of regeneration-adsorption showed almost any loss of the performances. Anthropogenic emissions of green-house gases and increasing CO 2 atmospheric concentration are considered the major causes of global warming and ocean acidification. Carbon capture and sequestration turned out to be a valuable strategy to help mitigating these problems, making it urgent to develop novel materials able to selectively capture CO 2 . Thus, in the present experimental study, a new system for CO 2 capture based on porous mullite (3Al 2 O 3 ⋅2SiO 2 ) substrates fabricated by Digital Light Processing and properly functionalized with Metal Organic Frameworks (MOFs) was developed. Printable ceramic pastes were obtained by mixing in proper amounts commercial mullite powders to a photocurable commercial resin with a dispersant and a sintering additive to optimize the rheological behaviour, printability, and solid loading. Then, different geometries were successfully shaped with high accuracy: bars, pellets, as well as monoliths with two structures, grid-like and Schwartz primitive triply periodic minimal surface (TPMS). After debinding and sintering of the samples, mullite substrates were successfully functionalized with HKUST-1 (Cu 3 (BTC) 2 ) crystals by a two-step solvothermal synthesis process. HKUST-1 powders, as well as blank and coated lattice monoliths were tested in a catalytic bench reactor under 1% CO 2 flux (99% He). Before each measurement samples were heated at 120 °C for 4 h under He flux for regeneration. The samples showed an efficient CO 2 adsorption capacity, and the regeneration efficiency led to reusable and durable systems. Preliminary results showed that the TPMS structure was a more efficient substrate than grid-like architecture for capturing CO 2 , because of its higher surface area. Thus, this study demonstrates how the combination between additive manufacturing and MOFs technologies can set the stage to produce efficient engineered systems for CO 2 capture.